class Bid 
	include Comparable 
	attr_accessor :estimate 
	def <=>(other_bid) 
		if self.estimate < other_bid.estimate 
			-1 
		elsif self.estimate > other_bid.estimate 
			1 
		else 
			0
		end
	end
end

bid1 = Bid.new  
bid2 = Bid.new  
bid1.estimate = 100 
bid2.estimate = 105 
puts bid1 < bid2 
